Francis curtis



P. CURTIS. SCREEN PLATE FOR PAPER MACHINERY,

No. 62,942. Patented Mar. 19, 1867.

@nitrh tat2is gaunt @ffm,

FRANCIS CURTIS, AUBURNDALE,MASSACHUSETTS, ASSIGNS ONE-HALF OF RIGHT TO WILLIAM RUSSELL &- SON, OF LAWRENCE, MASSACHUSETTS. Letters Patent No. 62,942, dated ll'arch 19, 1867.

IMPROVED SCREEN PLATE FOR PAPER MACHINERY.

TO ALL TO WHOM THESE PRESENTS SHALL COME:

Be it known that I, FRsNc'Is .CuR'rrs, of Auburndale, in the county of Middle sex, and State of Massachusetts, have invented a new and useful or Improved Screen 'Plate for Paper Machinery, and do hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawings, making part of this specification, and in which Figure 1 is a top view or plan.

Figure 2, a longitudinal section; and.

Figure 3, a transverse section of a screen plate or one section thereof, constructed in accordance with mv inventiom In the drawings above referred to, A denotes the body of the plate, and era the shallow and narrow slots or saw-kerfs, through which the paper pulp passes and is screwed, as it is termed, the bars or portions of thebody between the slots, being shown at dd, 8:0. The body of the screen is chambered or recessed below each slot, as seen at b in the drawings.

The above is the usual mode of construction of screen la' 35. M invention however does not consist in the construction of the plate but in the material of which it is composed, or of making it of hard rubber in place of the metallic ones-now used. The slots of the. metallic plate, in the operation of cutting them, have their lower edges left in a rough state or with a burr upon them, The threads or fibres of the paper pulp, in passing throughthese slots of the screen, are often stopped and collected by this rough edge or burr, and clog or fill up the slots, causing much inconvenience and loss of time in cleaning them. Furthermore, the bars between the slots of the metallic screen plate in time often become bent out'of place or out of vertical parallelism with each other, and by this means enlarge the area of the slots so that the pulp passes through them in large quantities and without being screened, an evil well understood by practical paper makers. Again, the acids contained more or less in the pulp or in its sizing, injuriously affect the material composing the metallic plate. The hard rubber plate of my invention can be manufactured at less cost than the metallic one,and is much more durable. In constructing the plate of hard rubber these evils are overcome and other advantages gained, which will readily show themselves to men practised in the art of paper'ma'king, and to whom this specification is chiefly-addressed: first, owing to the peculiar nature of the rubber there is no roughness or burr left upon the edges of the slots, whether they be cut by machinery'as the metallic ones are now cut, or whether they be formed by pressure in a mould during process of vulcanizing; second, by the elastic properties of the rubber the bars ddwill return to place automatically should they at any time be forced out of parallelism witheach other or otherwise misplaced or bent; third, the surface of the rubber is not in the least affected by the action of acids. In addition tothese facts, the hard rubber plate can be manufactured at less cost than the metallic one, and is infinitely more durable.

I claim as my invention- A screen plate for p. per machinery, constructed of the material known as hard rubber.

FRANCIS CURTIS.

Witnesses:

FREDERICK Oun'rrs, CHAS. E. CHESTER. 

